JP3617258B2 - Toroidal continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The toroidal type continuously variable transmission according to the present invention is used as an automatic transmission for automobiles, for example.
[0002]
[Prior art]
The use of a toroidal continuously variable transmission as schematically shown in FIGS. 4 to 5 has been studied as a transmission for automobiles. This toroidal type continuously variable transmission supports an input disk 2 concentrically with an input shaft 1 and is arranged concentrically with the input shaft 1 as disclosed in, for example, Japanese Utility Model Publication No. 62-71465. An output side disk 4 is fixed to the end of the output shaft 3. On the inner side of the casing containing the toroidal-type continuously variable transmission, trunnions 6 and 6 are provided that swing about pivots 5 and 5 that are twisted with respect to the input shaft 1 and the output shaft 3.
[0003]
Each of these trunnions 6 and 6 is provided with the pivots 5 and 5 on the outer side surfaces of both ends. Further, by supporting the base ends of the displacement shafts 7 and 7 at the center of the trunnions 6 and 6, and by swinging the trunnions 6 and 6 about the pivots 5 and 5, The inclination angle of the displacement shafts 7 and 7 can be adjusted freely. Power rollers 8 and 8 are rotatably supported around the displacement shafts 7 and 7 supported by the trunnions 6 and 6, respectively. The power rollers 8 and 8 are sandwiched between the input side and output side disks 2 and 4. The inner side surfaces 2a and 4a of the input side and output side discs 2 and 4 facing each other are each rotated by rotating a circular arc around the pivot shaft 5 around the input shaft 1 and the output shaft 3 respectively. The resulting concave surface. And the peripheral surfaces 8a and 8a of each power roller 8 and 8 formed in the spherical convex surface are made to contact | abut to the said inner surface 2a and 4a.
[0004]
A loading cam type pressing device 9 is provided between the input shaft 1 and the input side disk 2, and the pressing device 9 elastically presses the input side disk 2 toward the output side disk 4. Yes. The pressing device 9 includes a cam plate 10 that rotates together with the input shaft 1 and a plurality of (for example, four) rollers 12 and 12 held by a cage 11. A cam surface 13 that is an uneven surface extending in the circumferential direction is formed on one side surface (left side surface in FIGS. 4 to 5) of the cam plate 10, and the outer side surface (right side in FIGS. 4 to 5) of the input side disk 2 is formed. The same cam surface 14 is also formed on the surface). The plurality of rollers 12 and 12 are supported so as to be rotatable about a radial axis with respect to the center of the input shaft 1.
[0005]
When the toroidal type continuously variable transmission configured as described above is used, when the cam plate 10 rotates as the input shaft 1 rotates, the cam surface 13 causes the rollers 12 and 12 to move to the outer surface of the input side disk 2. The cam surface 14 is pressed. As a result, the input side disk 2 is pressed against the power rollers 8 and 8 and at the same time, based on the pressing between the pair of cam surfaces 13 and 14 and the plurality of rollers 12 and 12, The input side disk 2 rotates. Then, the rotation of the input side disk 2 is transmitted to the output side disk 4 through the power rollers 8 and 8, and the output shaft 3 fixed to the output side disk 4 is rotated.
[0006]
When the rotational speed ratio (transmission ratio) between the input shaft 1 and the output shaft 3 is changed, and when first decelerating between the input shaft 1 and the output shaft 3, each trunnion 6 is centered on the pivot shafts 5 and 5. 6, and the peripheral surfaces 8 a, 8 a of the power rollers 8, 8 are located near the center of the inner surface 2 a of the input disk 2 and the outer periphery of the inner surface 4 a of the output disk 4 as shown in FIG. The displacement shafts 7 and 7 are inclined so as to abut against the offset portions. On the other hand, when increasing the speed, the trunnions 6 and 6 are swung around the pivot shafts 5 and 5 so that the peripheral surfaces 8a and 8a of the power rollers 8 and 8 are as shown in FIG. The displacement shafts 7 and 7 are inclined so as to abut the outer peripheral portion of the inner side surface 2a of the input side disc 2 and the central portion of the inner side surface 4a of the output side disc 4 respectively. If the inclination angle of each of the displacement shafts 7 and 7 is set intermediate between those shown in FIGS. 4 and 5, an intermediate gear ratio can be obtained between the input shaft 1 and the output shaft 3.
[0007]
6 to 7 show a more specific toroidal type continuously variable transmission described in the microfilm of Japanese Utility Model Application No. 63-69293 (Japanese Utility Model Laid-Open No. 1-173552). The input side disk 2 and the output side disk 4 are rotatably supported around the input shaft 15 via needle bearings 16 and 16, respectively. Further, the cam plate 10 is spline-engaged with the outer peripheral surface of the end portion (left end portion in FIG. 6) of the input shaft 15, and the flange portion 17 prevents movement in the direction away from the input side disk 2. Then, a loading cam type pressing device 9 that rotates the input side disk 2 while pressing the input side disk 2 toward the output side disk 4 based on the rotation of the input shaft 15 by the cam plate 10 and the rollers 12 and 12. It is composed. An output gear 18 is coupled to the output side disk 4 by means of keys 19, 19, so that the output side disk 4 and the output gear 18 rotate in synchronization. The output gear 18 and a gear (not shown) meshed with the output gear 18 constitute the power take-out means for taking out the rotation of the output disk.
[0008]
The pivots 5, 5 provided at both ends of the pair of trunnions 6, 6 are swingable on the pair of support posts 20, 20 and can be displaced in the axial direction (front and back direction in FIG. 6, left and right direction in FIG. 7). I support it. The pair of support posts 20, 20 is a metal plate having sufficient rigidity, and a circular hole 21 formed in the center is fixed to the inner surface of the casing 22 or the side surface of the cylinder case 23 provided in the casing 22. By being externally fitted to the provided support pins 24a and 24b, it is supported inside the casing 22 so as to be swingable and displaceable in the axial direction of the pivots 5 and 5. In addition, circular support holes 25 and 25 are formed at both ends of the support posts 20 and 20, respectively. The pivots 5 and 5 are respectively connected to the support holes 25 and 25, respectively. It is supported by radial needle bearings 27, 27 having 26, 26. Based on these configurations, the trunnions 6 and 6 are supported in the casing 22 such that the trunnions 6 and 6 are freely swingable around the pivots 5 and 5 and displaced in the axial direction of the pivots 5 and 5. ing.
[0009]
The displacement shafts 7 and 7 are supported in the circular holes 52 and 52 formed in the middle part of the trunnions 6 and 6 supported in the casing 22 as described above. Each of these displacement shafts 7 and 7 has support shaft portions 28 and 28 and pivot shaft portions 29 and 29 that are parallel to each other and eccentric, respectively. Of these, the support shaft portions 28 and 28 are supported inside the circular holes 52 and 52 so as to be swingable through radial needle bearings 30 and 30. Further, power rollers 8 and 8 are rotatably supported around the pivot shaft portions 29 and 29 through radial rolling bearings such as radial needle bearings 31 and 31.
[0010]
The pair of displacement shafts 7 and 7 are provided at 180 ° opposite positions with the input shaft 15 as the center. The direction in which the pivot shafts 29 and 29 of the displacement shafts 7 and 7 are eccentric with respect to the support shafts 28 and 28 is the same with respect to the rotation direction of the input side and output side disks 2 and 4. It is set as the direction (left-right reverse direction in FIG. 7). Further, the eccentric direction is a direction substantially orthogonal to the arrangement direction of the input shaft 15 (the left-right direction in FIG. 6 and the front-back direction in FIG. 7). Accordingly, the power rollers 8 and 8 are supported so as to be slightly displaceable in the direction in which the input shaft 15 is disposed. As a result, due to variations in dimensional accuracy of the constituent parts or elastic deformation at the time of power transmission, the power rollers 8 and 8 are moved in the axial direction of the input shaft 15 (left and right direction in FIG. 6, FIG. 7). Even when it tends to be displaced in the direction of the front and back), this displacement can be absorbed without applying excessive force to each component.
[0011]
Further, between the outer surface of each of the power rollers 8 and 8 and the inner surface of the intermediate portion of each of the trunnions 6 and 6, thrust ball bearings 32 and 32, etc. in order from the outer surface side of the power rollers 8 and 8. A thrust rolling bearing and thrust bearings such as thrust needle bearings 34 and 34 for supporting a thrust load applied to the outer rings 33 and 33 described below are provided. Of these, the thrust ball bearings 32, 32 allow the power rollers 8, 8 to rotate while supporting a load in the thrust direction applied to the power rollers 8, 8. The thrust needle roller bearings 34, 34 support the thrust load applied to the outer rings 33, 33 of the thrust ball bearings 32, 32 from the power rollers 8, 8, while supporting the pivot shafts 29, 29. The outer rings 33 and 33 are allowed to swing around the support shafts 28 and 28.
[0012]
Further, driving rods 35 and 35 are coupled to one end portions (left end portions in FIG. 7) of the trunnions 6 and 6 respectively, and driving pistons 36 and 36 are fixed to the outer peripheral surfaces of the intermediate portions of the driving rods 35 and 35, respectively. Has been established. The drive pistons 36 and 36 are oil-tightly fitted in drive cylinders 37 and 37 provided in the cylinder case 23, respectively. Further, a pair of rolling bearings 39, 39 are provided between the support wall 38 provided in the casing 22 and the input shaft 15, and the input shaft 15 is rotatably supported in the casing 22. Yes.
[0013]
In the case of the toroidal type continuously variable transmission configured as described above, the rotation of the input shaft 15 is transmitted to the input side disk 2 via the pressing device 9. Then, the rotation of the input side disk 2 is transmitted to the output side disk 4 via a pair of power rollers 8 and 8, and the rotation of the output side disk 4 is further taken out from the output gear 18. When changing the rotational speed ratio between the input shaft 15 and the output gear 18, the pair of drive pistons 36, 36 are displaced in opposite directions. As the drive pistons 36 and 36 are displaced, the pair of trunnions 6 and 6 are displaced in the opposite directions. For example, the lower power roller 8 in FIG. The power rollers 8 are displaced to the left in the figure. As a result, the direction of the tangential force acting on the contact portion between the peripheral surfaces 8a, 8a of the power rollers 8, 8 and the inner side surfaces 2a, 4a of the input side disk 2 and the output side disk 4 changes. To do. As the force changes, the trunnions 6 and 6 swing in directions opposite to each other in FIG. 6 about the pivots 5 and 5 pivotally supported by the support posts 20 and 20. As a result, as shown in FIGS. 4 to 5 described above, the contact position between the peripheral surfaces 8a and 8a of the power rollers 8 and 8 and the inner surfaces 2a and 4a changes, and the input shaft 15 and The rotational speed ratio with the output gear 18 changes.
[0014]
When the power rollers 8 and 8 are displaced in the axial direction of the input shaft 15 as a result of elastic deformation of the constituent parts during power transmission, the displacement shafts pivotally supporting the power rollers 8 and 8 are used. 7 and 7 slightly swing around the support shafts 28 and 28. As a result of this swinging, the outer side surfaces of the outer rings 33, 33 of the thrust ball bearings 32, 32 and the inner side surfaces of the trunnions 6, 6 are relatively displaced. Since the thrust needle bearings 34, 34 exist between the outer surface and the inner surface, the force required for this relative displacement is small. Therefore, as described above, the force for changing the inclination angle of each displacement shaft 7, 7 can be small.
[0015]
[Problems to be solved by the invention]
In the case of the toroidal type continuously variable transmission configured and operated as described above, if the torque to be transmitted becomes excessive, the outer ring 33 constituting each thrust ball bearing 32, 32 based on the elastic deformation of each trunnion 6, 6; The durability of 33 may not be ensured. That is, when the toroidal continuously variable transmission is operated, the inner side surface of each trunnion 6, 6 (the surface facing the input shaft 15) is larger than the power rollers 8, 8 supported on each trunnion 6, 6. Thrust load is applied. Then, when the toroidal continuously variable transmission is operated, the trunnions 6 and 6 are curved in a direction in which the inner side surfaces thereof become concave as shown in an exaggerated manner in FIG. 8 based on this thrust load.
[0016]
When such bending occurs, the outer ring raceway 41 formed on the rolling surface of each of the plurality of balls 40, 40 constituting the thrust ball bearings 32, 32 and the inner surface of the outer rings 33, 33, 41 and the inner ring raceways 42 and 42 formed on the outer surfaces of the power rollers 8 and 8 become non-uniform. Specifically, the rolling surfaces of the balls 40, 40, the outer ring raceways 41, 41, and the inner ring, which are present on the left and right sides of FIGS. The contact pressure with the tracks 42, 42 increases. On the contrary, the rolling surfaces of the balls 40, 40 present on the left and right side portions in FIG. 6 and the outer ring raceways 41, 41 and the inner ring raceways 42, 42, which are present in the width direction both ends of each trunnion 6, 6, The contact pressure of becomes smaller.
[0017]
The power rollers 8 and 8 and the balls 40 and 40 rotate or revolve in accordance with the operation of the toroidal continuously variable transmission, so that the rolling surfaces and the inner ring raceways 42 and 42 receive loads almost evenly. Therefore, fatigue of the rolling surfaces and the inner ring raceways 42 and 42 does not proceed locally. On the other hand, the outer rings 33, 33 do not rotate by being externally fitted and fixed to a continuous portion of the support shaft portion 28 and the pivot shaft portion 29 at the intermediate portion of the displacement shaft 7. For this reason, in each of the outer ring raceways 41, 41, a large contact pressure is always applied to the same portion (a portion in the vicinity of both left and right ends in FIGS. 7 to 8), and fatigue of the portion progresses locally. As a result, the rolling fatigue life of the thrust ball bearings 32, 32 is shortened, which is not preferable for ensuring the durability of the toroidal type continuously variable transmission.
The toroidal continuously variable transmission of the present invention has been invented to eliminate the above-mentioned disadvantages.
[0018]
[Means for Solving the Problems]
The toroidal-type continuously variable transmission of the present invention includes an input shaft, an input-side disk rotatable with the input shaft, and the input-side disk, as in the above-described conventionally known toroidal-type continuously variable transmission. An output side disk arranged concentrically and supported rotatably with respect to the input side disk, power take-out means for taking out the rotation of the output side disk, and center axes of both the input side and output side disks A plurality of trunnions arranged at a twisted position and swinging at the positions, and a plurality of powers that are rotatably supported by displacement shafts supported by the trunnions and are sandwiched between both the input and output disks. These powers are mounted while supporting the thrust load applied to the power rollers provided between the rollers and the outer surfaces of the power rollers and the inner surfaces of the trunnions. It consists thrust rolling bearing to permit rotation of the roller. Then, the inner side surfaces of both the input side and output side discs facing each other are each a concave surface having a circular cross section, and the peripheral surface of each power roller is a spherical convex surface. Are in contact.
In particular, in the toroidal type continuously variable transmission according to the present invention, the annular outer ring constituting each thrust rolling bearing is rotatable around the middle portion of each displacement shaft and is rotatable around each displacement shaft. I support it.
[0019]
[Action]
With the toroidal-type continuously variable transmission of the present invention configured as described above, the operation when the rotational force is transmitted between the input side disk and the output side disk, and the gear ratio between these two disks are obtained. The action at the time of changing is the same as that of the conventional toroidal type continuously variable transmission described above.
In particular, in the case of the toroidal-type continuously variable transmission according to the present invention, the outer ring constituting each thrust rolling bearing is rotatably supported around the displacement shaft. The part that receives the load (the part where the contact pressure with the rolling surface is large) always changes. As a result, the outer ring raceway is not locally fatigued (the fatigue of the outer ring raceway proceeds evenly over the entire circumference), and the rolling fatigue life of the outer ring raceway can be extended.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an example of an embodiment of the present invention. The feature of the present invention is that the outer ring 33 constituting the thrust ball bearings 32 and 32 (see FIGS. 6 to 8), each of which is a thrust rolling bearing, is rotatably supported with respect to the displacement shaft 7. This is to extend the rolling fatigue life of the outer ring raceway 41 formed on the inner side surface 33 (upper surface in FIG. 1). Since the structure and operation of the other parts are the same as in the case of the above-described conventional structure, the illustration and description of the equivalent parts are omitted or simplified, and the following description will focus on the characteristic parts of the present invention.
[0021]
An annular (annular) outer ring 33 constituting each of the thrust ball bearings 32 is arranged in the middle of the displacement shaft 7 around the continuous portion of the support shaft portion 28 and the pivot shaft portion 29. It is supported rotatably around the center. For this reason, a circular center hole 46 in which the large diameter portion 43 and the small diameter portion 44 are continuously connected by the step portion 45 is formed in the center portion of the outer ring 33. The large-diameter portion 43 of the center hole 46 is externally fitted to the outward flange-like circular flange portion 47 formed in the intermediate portion of the displacement shaft 7 with a gap fit. For this reason, the inner diameter of the large-diameter portion 43 is slightly larger than the outer diameter of the flange portion 47. Further, the inner diameter of the small-diameter portion 44 is sufficiently larger than the outer diameter of the base end portion (lower end portion in FIG. 1) of the pivot shaft portion 29, and the outer peripheral surface of the base end portion of the pivot shaft portion 29. And a radial bearing such as a radial needle bearing 48 or a radial sliding bearing using a copper alloy is provided between the inner peripheral surface of the small-diameter portion 44.
[0022]
A thrust needle bearing 34 (see FIGS. 3 and 6-8) is provided between the outer surface of the outer ring 33 (the lower surface in FIGS. 1-2) and the inner surface of the trunnion 6 (see FIGS. 6-8). Therefore, the outer ring 33 is smoothly rotated around the displacement shaft 7 regardless of the thrust load applied to the outer ring 33. In order to perform this rotation smoothly, as shown in FIG. 3, among the plurality of needles 49, 49 constituting the thrust needle bearing 34, the needle 49 abutting on the outer surface of the outer ring 33, 49 is preferably arranged in the radial direction with the support shaft portion 28 as the center. If the needles 49 and 49 are arranged in this way, the needles 49 and 49 roll smoothly when the outer ring 33 rotates around the support shaft portion 28, and the needles around the displacement shaft 7. The outer ring 33 can be smoothly rotated. It should be noted that the arrangement direction of the needles 49, 49 and the radial direction centered on the support shaft portion 28 may coincide with each other in a state where the displacement shaft 7 exists at the neutral position (position shown in FIG. 3). .
[0023]
In addition, with the radial needle bearing 48 and the thrust needle bearing 34, the outer ring 33 is rotatably supported around the intermediate portion of the displacement shaft 7, and one side surface of the step portion 45 and the flange portion 47 ( The upper surface of FIGS. These outer surfaces and the inner peripheral surface of the large-diameter portion 43 and the outer peripheral surface of the flange portion 47 are made smooth so that the outer ring 33 around the displacement shaft 7 can be obtained even when the opposing surfaces contact each other. So that the rotation is smooth. However, if the rotational speed of the outer ring 33 with respect to the displacement shaft 7 becomes too fast, there is a problem in terms of durability, such as the wear of the contact portion between the stepped portion 45 and one side surface of the flange portion 47 easily progresses. Occurs. That is, the present invention aims to increase the durability of the outer ring raceway 41 provided on the inner surface of the outer ring 33 by rotating the outer ring 33 with respect to the displacement shaft 7. The rotation speed of 33 is preferably as slow as possible (for example, about 1 to several rpm) as long as the rotation is performed stably. In view of this, the contact portion between the step portion 45 and one side surface of the flange portion 47 and, if necessary, the contact portion between the inner peripheral surface of the large-diameter portion 43 and the outer peripheral surface of the flange portion 47 are suitably used. Thus, the rotational speed of the outer ring 33 with respect to the displacement shaft 7 is adjusted. If necessary, a friction adjusting member having a desired friction coefficient may be sandwiched between one or both of the contact portions.
[0024]
Further, the contact portion between the step portion 45 and one side surface of the flange portion 47, and if necessary, the contact portion between the inner peripheral surface of the large diameter portion 43 and the outer peripheral surface of the flange portion 47, It is preferable to perform a process for preventing wear of each surface constituting each of the contact portions. As such processing, the displacement shaft 7 (particularly the flange 47) and the outer ring 33 (particularly the inner diameter part) are made of a material having excellent wear resistance, or the contact part is formed. It can be considered that the surface to be constructed is subjected to a surface treatment having wear resistance such as nitriding treatment.
[0025]
In the case of the toroidal type continuously variable transmission of the present invention configured as described above, the outer ring 33 constituting each thrust ball bearing 32, 32 is rotatably supported around the intermediate portion of the displacement shaft 7. The outer ring 33 rotates based on the rolling resistance of the thrust ball bearings 32 and 32. For this reason, in the outer ring raceway 41 provided on the inner surface of the outer ring 33, a part that receives a large thrust load from the balls 40, 40 (see FIGS. 6 to 8) that are rolling elements (a part that has a large contact pressure with the rolling surface). ) Always changes. Therefore, the outer ring raceway 41 is not locally fatigued. In other words, the fatigue of the outer ring raceway 41 proceeds evenly over the entire circumference. As a result, the rolling fatigue life of the outer ring raceway 41 as a whole can be extended.
[0026]
【The invention's effect】
Since the present invention is configured and operates as described above, it is possible to improve the durability of the outer ring of the thrust rolling bearing and contribute to the improvement of the reliability and durability of the toroidal type continuously variable transmission incorporating this outer ring. .
[Brief description of the drawings]
FIG. 1 is a partial cutaway view showing a displacement shaft and an outer ring taken out, showing an example of an embodiment of the present invention.
FIG. 2 is an enlarged view of a portion A in FIG.
FIG. 3 is a perspective view of an inner surface portion of a trunnion incorporating a thrust ball bearing and a thrust needle bearing.
FIG. 4 is a schematic side view showing a basic configuration of a toroidal-type continuously variable transmission in a state of maximum deceleration.
FIG. 5 is a schematic side view showing the maximum speed increase state.
FIG. 6 is a cross-sectional view of an essential part showing an example of a specific structure conventionally known.
7 is a cross-sectional view taken along line BB in FIG.
8 is a schematic side view exaggeratingly showing a state in which the trunnion is elastically deformed based on a thrust load acting during operation, as viewed from the same direction as FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Input shaft 2 Input side disk 2a Inner side surface 3 Output shaft 4 Output side disk 4a Inner side surface 5 Pivot 6 Trunnion 7 Displacement shaft 8 Power roller 8a Circumferential surface 9 Pressing device 10 Cam plate 11 Retainer 12 Rollers 13, 14 Cam surface 15 Input shaft 16 Needle bearing 17 collar 18 output gear 19 key 20 support post 21 circular hole 22 casing 23 cylinder case 24a, 24b support pin 25 support hole 26 outer ring 27 radial needle bearing 28 support shaft 29 pivot shaft 30,30 Radial needle bearing 32 Thrust ball bearing 33 Outer ring 34 Thrust needle bearing 35 Drive rod 36 Drive piston 37 Drive cylinder 38 Support wall 39 Rolling bearing 40 Ball 41 Outer ring raceway 42 Inner ring raceway 43 Large diameter portion 44 Small diameter portion 45 Step portion 46 Center hole 47 Collar 48 radial needle bearing 49 needle

Claims (1)

An input shaft, an input side disk that is rotatable together with the input shaft, an output side disk that is arranged concentrically with the input side disk and is rotatably supported with respect to the input side disk, and rotation of the output side disk Power take-out means for taking out, a plurality of trunnions arranged at a twisted position with respect to the center axis of both the input side and output side discs, and rotating about a displacement shaft supported by each trunnion A plurality of power rollers supported freely and sandwiched between both the input and output disks, and provided between the outer surface of each of the power rollers and the inner surface of each of the trunnions. It consists of a thrust rolling bearing that supports the rotation of each power roller while supporting the applied thrust load, and both the input and output side disks face each other. In the toroidal continuously variable transmission in which the inner surface is a concave surface having an arc-shaped cross section and the peripheral surface of each power roller is a spherical convex surface, the peripheral surface is in contact with the inner surface. A toroidal-type continuously variable transmission characterized in that an annular outer ring constituting each thrust rolling bearing is supported around an intermediate portion of each displacement shaft so as to be rotatable around each displacement shaft.

Images